A good week of rain to soak some of NSW | Weather In Focus

A mass moisture-laden air from the tropics, associated with Ex-Tropical Cyclone Esther, is causing widespread rain and thunderstorms over NSW this week.

This system will affect parts of every district in NSW between Wednesday and Friday, delivering falls of 20 to 40 millimetres in many areas and more than 100mm in some places.

Weather patterns like this one were absent during 2019, which helped make that year the driest on record for NSW and Australia as a whole.

Fortunately, two of the climate drivers that underpinned last year's severe lack of rainfall - a positive Indian Ocean Dipole (IOD) and negative Southern Annular Mode (SAM) - both broke down at the beginning of 2020.

This shift in climate drivers saw a change in the weather patterns over south-eastern Australia, with a return of more frequent and heavier rain during the last couple of months.

While February was a good month for rain in the eastern half of NSW, many areas west of the ranges missed out.

This month, almost all of NSW should receive at least some rain during the opening week of March.

While this week's rain is welcome, it's unlikely to be drought-breaking.

During the 24 months to February 2020, most of NSW had accumulated rainfall deficits of more than 300mm.

Some areas were running more than 600mm below average at the end of this two-year period. It's going to take multiple months of above average rain to make up these deficiencies.

Thankfully, this month will go some way to replenishing the missing water across NSW.

March is likely to be the second consecutive month with above average rain in NSW, ending a 10-month run of drier-than-usual months up to January this year.